mm/Sub-mm Wave Compressive Sensing Imaging

在毫米波到太赫兹(毫米波-太赫兹，30 GHz-3太赫兹)电磁频谱范围内的成像为调查和感知我们周围的世界提供了一个新的维度。毫米波成像已被广泛用于机场的威胁探测和射电天文学的科学发现，以识别数千光年外的气体云中的粒子。太赫兹成像显示了一种研究生物组织的新手段，特别是在肿瘤筛查方面。虽然科学和社会效益是巨大的，但毫米波-太赫兹成像领域仍处于初级阶段。一个特别严峻的挑战是，在电路板上集成大量的毫米波-太赫兹传感器是不切实际的，因为每个“像素”的大小必须至少与波长成正比。不幸的是，使用单一传感器或少量传感器会使当前的毫米波-太赫兹成像系统速度太慢。在这项工作中，我们将研究一种新的毫米波-太赫兹成像方法，它使用压缩传感和数字毫米波-太赫兹可配置透镜，以提供高达32倍的分辨率或速度提高。压缩传感可以减少重建图像所需的信息，从而使光学成像仪需要的测量减少70%-80%。这种减少的关键是伪随机空间调制器或掩模的使用。然而，在毫米波-太赫兹频率中，由于每个调制器像素的大小需要至少与波长成正比，所以不存在这样的空间调制器。因此，毫米波-太赫兹无法利用这些新方法。在这个项目中，我们将结合几个研究领域，研究一种针对毫米波-太赫兹成像的变革性解决方案。首先，光子诱导动态空间调制器将用于毫米波-太赫兹频率。其次，先进的压缩传感算法将从减少的测量次数中重建高保真图像。第三，多传感器阵列将加速图像采集，信号处理算法将考虑所有传感器采集的图像的共享结构。由此产生的系统有可能提供每秒50-100帧的速度，并极大地提高了信噪比。

Imaging in the millimeter-wave to terahertz (mmw-THz, 30GHz-3THz) region of the electromagnetic spectrum provides a new dimension to the investigation and perception of the world around us. Millimeter wave imaging has been extensively used for threat detection at airports and for scientific discovery in radio astronomy to identify particles in gas clouds thousands of light years away. Terahertz imaging has shown a new means to investigate biological tissues, in particular in tumor screening. While the scientific and societal benefits are enormous, the field of mmw-THz imaging is still in its infancy. A particularly acute challenge is that it is impractical to integrate a large number of mmw-THz sensors on a circuit board, because the size of each "pixel" must be at least proportional to the wavelength. Unfortunately, using a single sensor or small number of sensors renders current mmw-THz imaging systems far too slow. In this work we will investigate a new method for mmw-THz imaging that uses compressive sensing and a digital mmw-THz configurable lens to provide up to a 32x improvement in resolution or speed.Compressive sensing allows a reduction in the information needed to reconstruct an image, thus enabling optical imagers that require 70-80% fewer measurements. Key to this reduction is the use of pseudorandom spatial modulators, or masks. In the mmw-THz frequencies, however, such spatial modulators do not exist, due to the size of each modulator "pixel" needing to be at least proportional to the wavelength. Consequently, mmw-THz has not been able to leverage these new approaches. In this project, we will investigate a transformative solution to mmw-THz imaging by combining several research areas. First, photon induced dynamic spatial modulators will be used for mmw-THz frequencies. Second, advanced compressive sensing algorithms will reconstruct high fidelity images from a reduced number of measurements. Third, multi-sensor arrays will accelerate the image acquisition, and signal processing algorithms will account for the shared structure of the image being acquired by all the sensors. The resulting system has the potential to provide speeds of 50-100 frames per second and greatly increased signal-to-noise ratio.